β Scribed by Stephen H. Jenkins
No coin nor oath required. For personal study only.
Selection of trees for food by a colony of beavers in central Massachusetts was studied from September 1972 through April 1974. The beavers exhibited both seasonal and year-to-year differences in preference for certain genera. Pine was selected against during fall but not spring, and there was a switch in preference from birch during fall 1972 to oak and witch hazel in fall 1973. These differences may partly reflect greater seasonal stability in concentrations of stored nutrients in coniferous tree bark than in deciduous tree bark, and greater year-to-year stability in bark concentrations of stored nutrients in non-mast-seeding species than in mast-seeding species (1972 was a mast year for oaks in central Massachusetts).
π SIMILAR VOLUMES
Seasonal and year-to-year variations of the frequency and the types of inversions were studied in a Southern Greek Drosophila melanogaster wild population. Seven samples were taken during the years 1973-1975. The results based on the study of 6,200 chromosome slides may be summarised as follows: (1